1. Field
The following description relates to an Ethernet switch, and more particularly, to a method for reducing power consumption in an Ethernet switch.
2. Description of the Related Art
In recent times interest has been increasing in low-power design and environment-friendly IT technologies in light of economic and environmental issues.
In line with these trends, an issue arises regarding the reduction of energy consumption in network equipment connected to the Internet. Especially, use of an Ethernet switch and terminals connected to Ethernet is gradually increasing, and is being developed in order to provide ever widening bandwidths. To provide a ever widening bandwidths, power consumption is inevitably increased. For example, an Ethernet link of 1 GB consumes 4 watts more of electricity than an Ethernet link of 100 MB, and an Ethernet link of 10 GB consumes about 10 to 20 watts more of electricity than the Ethernet link of 100 MB.
However, a utilization rate of such links is low and a bandwidth narrower than the maximum available bandwidth is invariably only used.
There is no relation between the power consumption and the utilization rate of the link. Using such characteristic, technologies have been introduced to reduce energy consumption in an Ethernet apparatus.
The Institute of Electrical and Electronics Engineers (IEEE) which is an international standardization organization for networking industry established IEEE802.3az Energy Efficient Ethernet group to research technologies for saving energy by using an Ethernet interface that lowers a link processing speed when not all network links are used.
For example, a technique called rapid PHY selection (RPS) is proposed based on the fact that an Ethernet link between a desktop computer and a switch is usually maintained in a pause to state in which there is no data transmission. According to RPS, a low-data-rate PHY is used when utilization of the link is low, and a high-data-rate PHY is used when utilization of the link is high, so that overall energy consumed by the desktop and the switch can be reduced. Also, an adaptive link rate (ALR) technology has been investigated, which controls a data rate of an Ethernet link according to the utilization rate of the Ethernet link, similar to RPS.
However, for the above-described techniques, solutions also have to be considered for issues such as a PHY interface exchange with a corresponding apparatus, negotiation for adjusting a transmission rate of a link and synchronization for preventing frame loss. Moreover, such techniques can be implemented in future Ethernet apparatuses, but cannot be easily applied to the existing Ethernet equipment.
Meanwhile, as a power reduction method applicable to the existing standard Ethernet switching apparatus, a method of periodically transmitting a PAUSE frame from an Ethernet switch to all Ethernet apparatuses connected to the Ethernet switch has been proposed.
This method periodically generates a PAUSE frame and transmits the PAUSE frame through all ports connected to the Ethernet switch. However, in this case, since the transmission of a PAUSE frame is performed based on a cycle, a data packet transfer is paused by the PAUSE frame transmitted according to the cycle even when the data packet is actively being transferred, and thus data transfer delay may occur.
In addition, since the Ethernet switch transmits the PAUSE frame through all connected links, packet transmission from Ethernet apparatuses having a high link utilization rate may be blocked. That is, it may be problematic in that packet transfer delay and resulting congestion may occur.